Hydatidiform Mole

Basics

A gestational trophoblastic disease (GTD), which originates from the placenta and can locally invade the uterus and/or metastasize
Tumor arises from gestational rather than maternal tissue
Potential to develop into a malignancy:
- Gestational trophoblastic neoplasia (GTN)
Complete mole:
- Estimated in 1/1,500 pregnancies
- Fetal tissue not present
- Diffuse chorionic villi swelling
- Diffuse trophoblastic hyperplasia
- Malignancy develops in 15–20%:
  - If metastasizes, usually to lung
- Genetics:
  - Karyotype: 46XX (80%); 46XY (20%)
  - Paternal DNA expressed
  - Enucleate egg fertilized by 2 sperm or by a haploid sperm that duplicates
Partial mole:
- Estimated in 1/750 pregnancies
- Fetal or embryonic tissue often present
- Focal chorionic villi swelling
- Focal trophoblastic hyperplasia
- Malignancy develops in 1–5%
- Genetics:
  - Karyotype: 90% are triploid 69XXX, 69XXY, rarely 69XYY
  - Maternal and paternal DNA
  - Haploid ovum fertilized by 2 sperms or haploid ovum duplicates and is fertilized by normal sperm
Twinning with normal pregnancy possible w/partial mole:
- Higher risk for persistent maternal disease and metastasis
- Possible to have normal infant

Largely unknown
Risk factors:
- Extremes of maternal age best estimated risk factor:
  - >35 yr old carries 2–7.5-fold risk
  - <15 yr old
- Previous molar pregnancy carries 1–2% risk in future pregnancies (10–15 times the risk for general population)
- Deficiency in animal fat and vitamin A
- Smoking (>15 cigs/d)
- Maternal blood type AB, A, or B
- History of infertility and/or spontaneous abortions
Varies based on geography:
- Asian countries have highest risk
- U.S. and Western Europe have lowest risk (1 per 1,000–1,500 live births)
- Reported up to 1 per 12–500 live births in other countries
Finding in 1 of 600 therapeutic abortions

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